Redistribution of sih bonds



United States Patent 3,398,177 REDISTRIBUTION 0F SiH BONDS HowardFranklin Stewart, Midland, Mich., assignor to Dow Corning Corporation,Midland, Mich., a corporation of Michigan No Drawing. Filed May 10,1965, Ser. No. 454,663 10 Claims. (Cl. 260-4482) This applicationrelates to the process of contacting at a temperature of 50 to 250 C.(a) a silicone reactant comprising at least one organosilicon compoundselected from the group consisting of silanes, polysilanes, silcarbanes,and polysiloxanes, said silicone reactant containing (1) ESlH bondswhere the silicon atoms so bonded are further bonded to no more than oneatom selected from the group consisting of halogen and oxygen atoms, and(2) at least one type of bond selected from the group consisting ofESiCl, ESiR, and siloxane, where the silicon atoms participating in saidbonds are each bonded to no more than two atoms selected from the groupconsisting of chlorine and Oxygen atoms, where R is selected from thegroup consisting of aryl, alkaryl, and lower alkoxy, the other bonds insaid silicone reactant consisting essentially of those selected from thegroup consisting of Si-monovalent aliphatic hydrocarbon, Si-monovalentcycloaliphatic hydrocarbon, Si-monovalent halohydrocarbon, Si-divalenthydrocarbon-Si, Si-divalent halohydrocarbon-Si, and Si-Si; with (b) analuminum silicate selected from the group consisting of acidic aluminumphyllosilicates, and acidic aluminum silicates of zeolite structurehaving a port size sufliciently large to permit entry of said siliconereactant into said zeolite structure, whereby an exchange reactionoccurs between said bonds (1) and (2).

The process of this invention is a useful tool for transforming oneorganosilicon compound into another by means of acid clay catalysts,which have the advantage of being readily separable from the reactionmixture.

Ingredient (a) can be any of one or more organosilicon compounds thatcontain the requisite bonds described above.

The material that makes up ingredient (a) must contain silicon-bondedorganic radicals connected to the silicon by a ESlCE linkage, therebypreferably being an average of at least one organic group bonded to eachsilicon atom.

Examples of suitable monovalent aliphatic and cycloaliphatic hydrocarbongroups to which the silicon atoms can be bonded are alkyl and cycloalkylradicals such as methyl, ethyl, isopropyl, sec-hexyl, octadecyl, andcyclohexyl; and aliphatically unsaturated radicals such as ethynyl,vinyl, allyl, 4-hexenyl, and cyclopentenyl.

Examples of monovalent halohydrocarbon radicals are haloalkyl andhalocycloalkyl radicals such as 3,3,3-trifluoropropyl, S-chlorohexyl,and dib'romocyclopentyl; aliphatically unsaturated radicals such as4-bromobutenyl-Z and trifluorocyclohexenyl; and aryl-containing radicalssuch as chlorophenyl, dibromophenyl, a,a, x-trifiuorotolyl andiodoxenyl.

Examples of divalent hydrocarbon and halohydrocarbon radicals aremethylene, hexamethylene,

phenylene, xenylene, chlorophenylene, and tetrafluorophenylene.

R, defined above, can be any aryl or alkaryl radical such as phenyl,xenyl, tolyl, and m-ethylphenyl, or any lower alkoxy group such asmethoxy, ethoxy, or isopropoxy.

ice

. 2 Examples of suitable ingredients (a) are, therefore,

H SiO SiH, Hsi-o-siH, c na sim, C H SiCl, cHQJI :113 311 Jim 1113 j a rA F3 CF;

and v 4 CH3 q CH3 (Hi. H out dczr'n 0H,, o'n, on, 'c n,

and O 0 CH3 CH3 HSi-SiH, HS iCHgCH OHCHQCIhEEiH O 0 CH3 (341% (kHz and(CHshSiO s10 suoHm 2 JJFK 10 CH3 CH3 oH30 ,sicmoHrsi-o-siomomsnoomn and(CHahSlHg CH3 CH3 on; It; on; CH3

HS|i-SiH and (onmsxoonm, (cHmsiH,

0H; CH3

and

CH CH3 omQ-snomn, and HSi-O-S'iH and (IE3 z K ah M) Further examples ofingredient (a) are shown below.

Ingredient (b) can be any acidic aluminum silicate 6 as described above.An acidic aluminum silicate is one that can be titrated with alkali toyield a neutral mixture which is no longer catalytically active, butwhich can be reactivated by treatment with a strong acid such as HCl.The acid groups can be bound on the aluminum silicate as in naturalclay. In that case an aqueous dispersion of the clay will be neutral toacid test paper. The acid groups can also be placed on the aluminumsilicate by washing it in an aqueous inorganic acid solution. An aqueousdispersion of this will be acidic.

The phyllosilicates possess a sheet or platelike crystal structure, themost common genus. of the group being the clay family. Many clays arenaturally acidic; the others can be rendered acidic by acid-washing toremove the neutralizing alkali metal or alkaline earth cations.

Suitable clays for ingredient (b) are, for example, kaolinite, nacrite,halloysite, montmorillonite, bentonite, vermiculite, nontronite, illite,chlorite, a'nda'ttapulgite.

Other suitable phyllosilicates are the micas which have beenacid-treated to replace some of the alkali metal cations with hydrogenions.

Further information concerning the phyllosilicates is available in TheEncyclopedia of Chemical Technology, Interscience, New York (1959), vol.12, pp. 288292.

The zeolites consist primarily of aluminum silicate in a crystallineform of linked tetrahedral groups that form cagelike structures. Thesecages contain ports," which are passages into the interior of thecagelike zeolite structure. A cation is found in each of these cages,the zeolite being acidic when the cation is a proton or a hyd-roniumion. The zeolites are hydrated.

Examples of operative zeolites are acidic forms of analcite, chabazite,natrolite, scolecite, mordenite, heulandite, and phillipsite.

Operative zeolites must have ports that are large enough to permit entryof the silicone reactant into the cage structure of the zeolite. Theport size is the maximum width of openings into the zeolite structure,and it can be determined by theoretical means, or by attempting to reacta silicone reactant of known size with an acidic zeolite of unknown portsize. Failure to react in the manner described above is an indicationthat the port size is too small. Generally, the port size must be atleast 5, and preferably at least angstroms in order to accommodate theaverage silicone reactant.

Further information on aluminum silicates of zeolite structure isavailable in The Encyclopedia of Chemical Technology, ibid., pp.295-298.

All of the above aluminum silicates can be enhanced in their acidity bywashing them in solutions of aqueous strong inorganic acids such as HClor H 80 or by other acid treatment, followed by heating.

Another of many sources of information about clay is Grim, ClayMinerology, McGraw-Hill, New York (1953).

Virtually no natural aluminum silicate exists in the pure form, andimpurities in the aluminum silicate catalysts of this invention are notintended to place them outside of the scope of the claims below as longas they continue to operate in the manner described herein. Typicalimpurities are water, Fe O FeO, MgO, CaO, K 0, Na O, TiO and organicmaterials.

It is preferred to operate the process of this invention at atemperature below 200 C.; the process of this invention is practicallyalways operative at temperatures below that point.

The time of reaction varies with the temperature and the nature of thereactants involved, but rarely exceeds a few hours.

Other materials such as organic solvents and nonreactive organosiliconcompounds can be present in the process of this application, if desired.

The redistribution of SiH bonds with the bonds of category (2) appearsto be generally random in that all possible redistribution products areusually produced, but the yields of the products may vary with thereaction conditions, nature of the catalysts, etc.

The following examples are illustrative only, and should not beconstrued as limiting the invention, which is properly delineated in theappended claims.

Example 1 A quantity of (CHahSiOSKCHa):

was heated at 58 to 73 C. in the presence of an H SO treatedbentonite-type clay which is sold under the name of Fi1trol-13 forseveral hours. The following new products were formed: (CH SiH (gas) andcompounds of the formula CH3 (CH SiO(SiO suonm where n has an averagevalue of 129. Compounds where n is 1 through 7 were isolated.

Example 2 (a) A quantity of (ombsiosuom was heated at about 109 C. forseveral hours in the presence of the clay of Example 1.

The products (Cl-l SiH (gas) and (CH SiOSi (CH 3 were recovered.

(b) A quantity of CHaCHgCHflCHBlz lOfiKCHa)1 was heated at about 109 C.for several hours in the presence of the clay of Example 1. The products(CH SiI-I and $11 CH3 CHgClIzCHgSi-O-SiCHzCHgCHa CH3 Ha were recovered.

(c) The above experiment was repeated, using CH SiH was recovered alongwith an undetermined number of other compounds, indicating that therehad been a redistribution of ESlH,

and siloxane bonds.

Example 3 A quantity of i (oumsiosio-suonm H H3 H was heated at 83 C. inthe presence of the clay of Example 1 for several hours.

The following new products were formed:

(CH SiH and A mixture of 0.34

was heated at 110 C. in the presence of 0.04 g. of the clay of Example 1under pressure for several hours.

The product CH3 CH3 on, Ht... 4...

1H n JIHJ I wasrformed, where n had an average value of 15.6, but thepresence of materials where n is from 0 to 11 was also detected.

- ExampleS pm (CHshHSiO S'iO sucnm (3H3 (CHmHSiO SiO SiH(CH where .n hasa value of 0 through 7, were identified.

Example 6 A mixture of (CH SiH and octamethylcyclotetrasiloxane washeated at 110 to 114 C. in the presence of the clay of Example 1 forseveral hours.

The product was r s t (OHmSiO SiO suom):

where n has a value of 4 to 20.

Example 7 A quantity of phenyldimethylsilane was heated at 105 C. in thepresence of the clay of Example 1 for several hours. i

There was recovered a 27% yield of diphenyldimethylsilane anda 26% yieldof dimethylsilane.

. Example 8 Example 9 A quantity of dimethylethoxysilane was heated at104 C. in the presence of the clay of Example 1 for several hours.

Among the products were dimethylsilane and dimethyldiethoxysilane.

Example 10 A quantity of phenylmethylchlorosilane was heated at 63 to115 C. in the presence of the clay of Exampie 1 for several hours.

There was recovered a 35% yield of methylsilane along with a substantialamount of phenylmethyldichlorosilane and diphenylmethylchlorosilane.

Example 11 Equimolar amounts of phenyldimethylsilane anddiphenyldichlorosilane were heated at to C. in the presence of the clayof Example 1 for several hours. The products included silane,dimethyldichlorosilane, dimethylsilane, triphenylchlorosilane,diphenylchlorosi lane and diphenylsilane.

Example 12 v Mixtures of 25 microliters of sym-tetramethyldisiloxaneand. 0.001 g. of one of the following catalysts were heated at 109 C.for 23 hours.

The product was analyzed for the presence .of (CH SiH =by gas-liquidchromatography.

The catalysts used, and the area percent of the recorded chromatographicpeaks that pertained to are shown below. This latter figure relates tothe yield of (CH SiH in a nonlinear manner, but a high area percentindicates a high yield.

Area percent of Catalyst: (CH SiI-I (a) The clay of Example 1 77.0 (b) Asynthetic, acid-activated mordenite having a molecular sieve structure,and known as Zeolon H+ (Norton Chemical Co.) 79.5 (c) Colloidal,naturally acidic kaolin (Fisher chemical) 89.6 (d) Acid-washed kaolin66.4

(e) An aluminum silicate of zeolite structure having an average cagesize of 80 A. (Houdry S-46) 34.6 (f) Naturally acidic hall'oysite 87.6(g) H SO -washed fullers earth (containing attapulgite) 79.6 (h) Naturalattapulgite 6.0

Example 13 When sym-bis-3,3,3-trifluoropropylmethyldisiloxane is heatedfor 12 hours at 150 C. in the presence of powdered, acidicmontrnorill'onite, the products 3,3,3 -triflu0ropropylmethylsilane andare formed, where n has a value of 3 to 40.

Example 14 When is heated for 12 hours at 150 C. in the presence ofacidic ral where n has a value of 3 to 20.

7 Example 15 When 1 g. of

7 CH3 CH3 HSi-SiH (1H3 (5H3 is heated with 1 g. of

(GHs)aSlO(Si)aSl(CHa)a at 100 C. in the presence of natural, acidichalloysite, the products (CH );,-'SiH and a poly(siloxanesilane) residueare formed.

Example 16 When 1 g. of

CH CH HOSi SiOH 43H; (IE3 is reacted at 100 C. with 1 g. of

CH3 CH3 HSiCH CH1OFzCH1CH S iH CH3 H3 in the presence of an acidic,aluminum silicate zeolite having an average port size of 10 A., theproducts i nosrOsron 5 0 among others, are recovered.

That which is claimed is: 1. The process of contacting at a temperatureof 50 to 250 C.

(a) a silicone reactant comprising at least one organosilicon compoundselected from the group consisting of silanes, polysilanes, andpolysiloxanes, said silicone reactant containing (1) ESiI-I bonds wherethe silicon atoms so bonded are further bonded to no more than one atomselected from the group consisting of halogen and oxygen atoms, and

(2) at least one type of bond selected from the group consisting ofESiCl, ::SiR, and siloxane, where the silicon atoms participating insaid bonds are each bonded to no more than two atoms selected from thegroup consisting of chlorine and oxygen atoms, where R is selected fromthe group consisting of aryl, alkaryl, and lower alkoxy, the other bondsin said silicone reactant consisting essentially of those selected fromthe group consisting of Si-monovalent aliphatic hydrocarbon,Si-monovalent 'cycloaliphatic hydrocarbon, Si-monovalcnthalo-hydrocarbon, Si-divalent hydrocarbon-Si, Si-divalenthalohydrocarbon-Si, and Si-Si; with (b) an aluminum silicate selectedfrom the group consisting of acidic aluminum phyllosilicates, and acidicaluminum silicates of zeolite structure having a port size sufiicientlylarge to permit entry of said silicone reactant into the zeoliteframework, whereby an we change reaction occurs between said bonds (1)and (2).

2. The process of claim 1 where the silicon reactant contains ESiOSiEbonds.

3. The process of claim 1 where the silicone reactant contains ESiClbonds.

4. The process of claim 1 where the silicone reactant contains E'SiC H5bonds.

5. The process of claim 1 where the silicone reactant containssilicon-lower alkoxy bonds.

6. The process of claim 1 where (b) has a zeolite structure.

7. The process of claim 1 where (b) is a bentonite clay which has beentreated with a strong inorganic acid.

8. The process of claim 1 where (b) is acidic kaolin.

9. The process of claim 1 where (b) is acidic halloysite.

10. The process of claim 1 where (b) is acidic montmorillonite.

References Cited UNITED STATES PATENTS 2,717,257 9/1955 Bluestein260-4482 3,346,349 10/ 1967 Harding et al 23-366 XR HELEN M. MCCARTHY,Primary Examiner.

I. P. PODGORSKI, Assistant Examiner.

1. THE PROCESS OF CONTACTING AT A TEMPERATURE OF 50* TO 250*C. (A) ASILICONE REACTANT COMPRISING AT LEAST ONE ORGANOSILICON COMPOUNDSELECTED FROM THE GROUP CONSISTING OF SILANES, POLYSILANES, ANDPOLYSILOXANES, SAID SILICONE REACTANT CONTAINING (1) $SIH BONDS WHERETHE SILICON ATOMS SO BONDED ARE FURTHER BONDED TO NO MORE THAN ONE ATOMSELECTED FROM THE GROUP CONSISTING OF HALOGEN AND OXYGEN ATOMS, AND (2)AT LEAST ONE TYPE OF BOND SELECTED FROM THE GROUP CONSISTING OF $SICL,$SIR, AND SILOXANE, WHERE THE SILICON ATOMS PARTICPATING IN SAID BONDSARE EACH BONDED TO NO MORE THAN TWO ATOMS SELECTED FROM THE GROUPCONSISTING OF CHLORINE AND OXYGEN ATOMS, WHERE R IS SELECTED FROM THEGROUP CONSISTING OF ARYL, ALKARYL, AND LOWER ALKOXY, THE OTHER BONDS INSAID SILICONE REACTANT CONSISTING ESSENTIALLY OF THOSE SELECTED FROM THEGROUP CONSISTING ESSENTIALLY OF THOSE SELECTED FROM THE GROUP CONSISTINGOF SI-MONOVALENT ALIPHATIC HYCARBON, SI-MONOVALENT HALO-HYDROCARBON,SI-DIVALENT HYDROCARBON-SI, SI-DIVALENT HALOHYDROCARCARBON-SI, ANDSI-SI; WITH (B) AN ALUMINUM SILICATE SELECTED FROM THE GROUP CONSISTINGOF ACIDIC ALUMINUM PHYLLOSILICATES, AND ACIDIC ALUMINUM SILICATES OFZEOLITE STRUCTURE HAVING A PORT SIZE SUFFICIENTLY LARGE TO PERMIT ENTRYOF SAID SILICONE REACTANT INTO THE ZEOLITE FRAMEWORK, WHEREBY ANEXCHANGE REACTION OCCURS BETWEEN SAID BONDS (1) AND CHANGE REACTIONOCCURS BETWEEN SAID BONDS (1) AND (2).